<template>
  <div class="spec-preview">
    <img v-if="skuImageList[currentIndex]" :src="skuImageList[currentIndex].imgUrl" />
    <div class="event" @mousemove="handlerFn"></div>
    <div class="big">
      <img ref="big" v-if="skuImageList[currentIndex]" :src="skuImageList[currentIndex].imgUrl" />
    </div>
    <div ref="mask" class="mask"></div>
  </div>
</template>

<script>
  export default {
    name: "Zoom",
    props: {
      skuImageList: {
        type: Array,
        require: true
      }
    },
    data () {
      return {
        currentIndex: 0
      }
    },
    methods: {
      // 鼠标在图片中移动触发的事件
      handlerFn(event){
        let mask = this.$refs.mask
        let big = this.$refs.big
        let maskLeft = event.offsetX - mask.offsetWidth / 2
        let maskTop = event.offsetY - mask.offsetHeight / 2
        // 约束范围
        maskLeft = maskLeft <= 0 ? 0 : event.offsetX - mask.offsetWidth / 2
        maskTop = maskTop <= 0 ? 0 : event.offsetY - mask.offsetHeight / 2
        if (maskLeft >= mask.offsetWidth) {
          maskLeft = mask.offsetWidth
        }
        if (maskTop >= mask.offsetHeight) {
          maskTop = mask.offsetHeight
        }
        // 修改蒙版的位置
        mask.style.left = maskLeft + 'px'
        mask.style.top = maskTop + 'px'
        big.style.left = -maskLeft + 'px'
        big.style.top = -maskTop + 'px'
      }
    },
    mounted () {
      // 接收兄弟发给的全局事件总线
      this.$bus.$on('getIndex',(i)=>{
        // console.log(i);
        this.currentIndex = i
      })
    }
  }
</script>

<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>